The present invention relates to methods and apparatus for reinforcing structural members, such as structural sections used as automotive components.
In a number of applications, particularly in the automotive industry there is a need for light-weight, high-strength structural members. Although structural members having these characteristics can be readily obtained through the use of various metal alloys, such as titanium alloys and the like, light-weight, high-strength alloys are generally cost prohibitive in automotive applications where weight reductions are closely balanced against the cost of materials. Moreover, reinforcement techniques are required which can be readily adapted to existing geometries of structural parts thereby eliminating the need for fundamental design changes and providing a means by which substandard design performance can be remedied. That is, in many instances, design deficiencies are discovered after the vehicle design has reached a stage at which radical changes are no longer feasible.
In addition, a significant amount of emphasis has been placed on performance characteristics of channel-shaped structural components which encounter forces that produce bending. Such structural components may be curved, hollow structural sections, such as automotive compartment rails or may be channel-shaped sections where two opposing section walls need to be secured together. My U.S. Pat. No. 5,575,926 discloses a composite laminate beam having an outer structural portion which is channel shaped and wherein an inner tube is disposed within the channel. A structural foam layer is bonded to the inner tube and the outer structural portion.
It would be desirable if techniques could be provided for providing sufficient reinforcement, particularly to curved hollow structural sections or to tie together two opposing sections.
An object of this invention is to provide a reinforced structure which meets the above needs.
A further object of this invention is to provide a method of reinforcing a channel-shaped structural member.
In accordance with this invention a reinforced structure comprises a channel shaped structural member and a reinforcement housing within the channel of the member. In one embodiment, the housing has a pair of opposite side walls with end walls being open. The axis of the housing which lies between the side walls and extends through the open ends is perpendicular to the longitudinal axis of the channel. A structural foam is in the housing and is bonded to the side walls of the structural member and to the housing to provide support for the structural member at the location of the housing.
In one practice of the invention the structural member is a curved hollow section, such as an automotive compartment rail.
The housing is preferably made as an extrusion which has support walls which are wide and flat. The structural foam is preferably an expandable polymer layer that is bonded to the housing support walls and upon expansion becomes bonded to the side walls of the structural member to tie the extrusion and structural member together. By having the housing as a drop-in part, it is possible to customize the shape of the housing for being placed at any desired location in the structural member.
In an alternative embodiment of the invention a hollow frame is provided to serve as a mounting structure for the foam layer. The frame is free of barriers or side walls along the sides of the foam that are disposed toward the side walls of the structural member so that the structural foam could be bonded directly to the side walls of the structural member.